All solid state battery

ABSTRACT

The main object of the present invention is to provide an all solid state battery suitable for high rate charging. The present invention solves the problem by providing an all solid state battery including a battery element having a cathode active material layer, an anode active material layer, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer, characterized in that the anode active material layer contains graphite as an anode active material and a sulfide solid electrolyte, the graphite has a hardness of 0.36 GPa or more by a nanoindentation method, and the battery element is confined at a pressure more than 75 kgf/cm 2 .

TECHNICAL FIELD

The present invention relates to an all solid state battery suitable forhigh rate charging.

BACKGROUND ART

For example, a lithium battery has been widely put to practical use inthe field of information relevant apparatuses and communicationapparatuses by reason of having a high electromotive force and a highenergy density. On the other hand, the development of an electricautomobile and a hybrid automobile has been hastened also in the fieldof automobiles from the viewpoint of environmental issues and resourceproblems, and a lithium battery has been studied also as a power sourcethereof.

Liquid electrolyte containing a flammable organic solvent is used for apresently commercialized lithium battery, so that the installation of asafety device for restraining temperature rise during a short circuitand the improvement in structure and material for preventing the shortcircuit are necessary therefor. In contrast, an all solid lithiumbattery all-solidified by replacing the liquid electrolyte with a solidelectrolyte layer is conceived to intend the simplification of thesafety device and be excellent in production cost and productivity forthe reason that the flammable organic solvent is not used in thebattery.

Such an all solid state battery generally has a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer. For example, in Patent Literature 1, an all solid statebattery having a solid electrolyte layer with a film thickness of 10 μmto 300 μm and a voidage of 30% or less, containing a sulfide solidelectrolyte, is disclosed. Also, pressurizing at a pressure of 30 MPa to1000 MPa (306 kgf/cm² to 10200 kgf/cm²) is disclosed as a method formaking a voidage of the electrolyte layer into 30% or less.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Publication (JP-A) No.2009-176541

SUMMARY OF INVENTION Technical Problem

The improvement of charging characteristics at high rate is claimed foran all solid state battery. It is conceived to be necessary to controlthe next four factors for input characteristics in high rate charging.That is to say, it is conceived to be necessary to control confiningpressure of a battery element, voidage of an anode active materiallayer, orientation property of an anode active material layer, andhardness of an anode active material. However, in Patent Literature 1,the problem is that the control of the four factors described above isso insufficient that input characteristics in high rate chargingdeteriorate. The present invention has been made in view of the actualcircumstances, and the main object thereof is to provide an all solidstate battery suitable for high rate charging.

Solution to Problem

In order to achieve the above-described object, in the presentinvention, there is provided an all solid state battery comprising abattery element having a cathode active material layer, an anode activematerial layer, and a solid electrolyte layer formed between the cathodeactive material layer and the anode active material layer, characterizedin that the anode active material layer contains graphite as an anodeactive material and a sulfide solid electrolyte, the graphite has ahardness of 0.36 GPa or more by a nanoindentation method, and thebattery element is confined at a pressure more than 75 kgf/cm².

According to the present invention, the graphite as an anode activematerial has a predetermined hardness and the battery element isconfined at a predetermined pressure (confining pressure), so that inputcharacteristics during high rate charging improve. Thus, an all solidstate battery suitable for high rate charging may be obtained.

Further, in the present invention, there is provided an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has an I₀₀₂/I₁₁₀ value of 200 or less afterpressing at a pressure of 4.3 ton/cm² in the case of regarding X-raydiffraction intensity of a peak on (002) plane as I₀₀₂ and X-raydiffraction intensity of a peak on (110) plane as I₁₁₀, and the batteryelement is confined at a pressure more than 75 kgf/cm².

According to the present invention, the I₀₀₂/I₁₁₀ value is within apredetermined range and the battery element is pressured at apredetermined pressure (confining pressure), so that inputcharacteristics during high rate charging improve. Thus, an all solidstate battery suitable for high rate charging may be obtained.

Further, in the present invention, there is provided an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has a hardness of 0.36 GPa or more by ananoindentation method, and a voidage of the anode active material layeris 30% or less.

According to the present invention, the graphite as an anode activematerial has a predetermined hardness and the voidage of the anodeactive material layer is within a predetermined range, so that inputcharacteristics during high rate charging improve. Thus, an all solidstate battery suitable for high rate charging may be obtained.

Further, in the present invention, there is provided an all solid statebattery comprising a battery element having a cathode active material-layer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has an I₀₀₂/I₁₁₀ value of 200 or less afterpressing at a pressure of 4.3 ton/cm² in the case of regarding X-raydiffraction intensity of a peak on (002) plane as I₀₀₂ and X-raydiffraction intensity of a peak on (110) plane as I₁₁₀, and a voidage ofthe anode active material layer is 30% or less.

According to the present invention, the I₀₀₂/I₁₁₀ value is within apredetermined range and the voidage of the anode active material layeris within a predetermined range, so that input characteristics duringhigh rate charging improve. Thus, an all solid state battery suitablefor high rate charging may be obtained.

Advantageous Effects of Invention

The present invention produces the effect such as to allow an all solidstate battery suitable for high rate charging.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an example of an allsolid state battery of the present invention.

FIG. 2 is a schematic view explaining an example of an anode activematerial layer in the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of a layerstructure of graphite.

FIG. 4 is a schematic view explaining another example of an anode activematerial layer in the present invention.

FIG. 5 is a schematic view explaining another example of an anode activematerial layer in the present invention.

FIG. 6 is a schematic view explaining another example of an anode activematerial layer in the present invention.

DESCRIPTION OF EMBODIMENTS

An all solid state battery of the present invention may be roughlydivided into four embodiments.

Each of the embodiments is hereinafter described.

1. First Embodiment

The all solid state battery of a first embodiment is an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has a hardness of 0.36 GPa or more by ananoindentation method, and the battery element is confined at apressure more than 75 kgf/cm².

FIG. 1 is a schematic cross-sectional view showing an example of the allsolid state battery of the first embodiment. An all solid state battery10 in FIG. 1 comprises a battery element 6 having a cathode activematerial layer 1, an anode active material layer 2, and a solidelectrolyte layer 3 formed between the cathode active material layer 1and the anode active material layer 2. The battery element 6 further hasa cathode current collector 4 formed on the surface of the cathodeactive material layer 1 opposite to the solid electrolyte layer 2, andan anode current collector 5 formed on the surface of the anode activematerial layer 2 opposite to the solid electrolyte layer 3.

FIG. 2 is a schematic view showing an example of an anode activematerial layer included in the all solid state battery in theembodiment. As shown in FIG. 2, the anode active material layer 2contains graphite 2 a as an anode active material and a sulfide solidelectrolyte (not shown in the figure). With regard to the graphite 2 a,a hardness calculated by a nanoindentation method is 0.36 GPa or more.Also, the battery element 6 is confined at a pressure (confiningpressure) more than 75 kgf/cm².

According to the embodiment, the anode active material layer has thegraphite, in which hardness by a nanoindentation method is apredetermined value or more, as an anode active material and the batteryelement is confined at a predetermined pressure (confining pressure), sothat input characteristics during high rate charging improve. Thus, anall solid state battery suitable for high rate charging may be obtained.

Thus, the reason why the graphite has a predetermined hardness and thebattery element is confined at confining pressure of a predeterminedvalue and thereby input characteristics during high rate chargingimprove is guessed as follows. In the case where the graphite as ananode active material does not have a predetermined hardness, it isconceived that the battery element is confined at such a predeterminedconfining pressure that the shape of the graphite changes and a functionas the active material deteriorates. Here, FIG. 3 is a schematic viewshowing an example of a layer structure of the graphite. As shown inFIG. 3, the graphite has a layer structure, and an edge plane on which aconductive ion (such as Li ion) is inserted and desorbed and a basalplane on which it is not inserted and desorbed exist on the surface ofthe graphite. Also, the ratio between the two planes on the surface ofthe graphite changes in accordance with shape change of the graphite. Inthe graphite not having a predetermined hardness, it is conceived thatthe shape of the graphite may not sufficiently be retained due toconfining pressure of the battery element, the ratio of the edge planeexisting on the surface of the graphite decreases relatively, and theratio of the basal plane increases relatively. Accordingly, it isconceived that an ion conduction path and an electron conduction pathare not secured, and a function of the graphite as the active materialdeteriorates. In contrast, in the embodiment, the graphite has such apredetermined hardness that the shape of the graphite may be retainedeven though the battery element is confined at a predetermined confiningpressure. Thus, it is conceived that the ratio of the edge planeexisting on the surface of the graphite is maintained and an ionconduction path is secured. Accordingly, a function of the graphite asthe active material is maintained. Also, in the embodiment, it isconceived that the battery element is confined at such a predeterminedconfining pressure that a sulfide solid electrolyte is crushed somoderately as to easily enter a gap in the graphite. Thus, an anodeactive material layer more excellent in ion conductivity may beobtained. Accordingly, input characteristics during high rate chargingimprove and an all solid state battery suitable for high rate chargingmay be obtained.

The all solid state battery of the embodiment is hereinafter describedin each constitution.

(1) Anode Active Material Layer

The anode active material layer in the embodiment is a layer containinggraphite as an anode active material and a sulfide solid electrolyte.

(i) Anode Active Material

With regard to the graphite as an anode active material in theembodiment, a hardness by a nanoindentation method (an indentationmethod) is ordinarily 0.36 GPa or more, preferably 0.40 GPa or more. Thereason therefor is that the case where the hardness of the graphite isless than the range brings a possibility that the battery element isconfined at such a predetermined confining pressure that the shape ofthe graphite may not be retained. That is to say, the ratio of the edgeplane existing on the surface of the graphite decreases relatively andthe ratio of the basal plane increases relatively, so that an ionconduction path and an electron conduction path are not secured and afunction of the graphite as the active material deteriorates. Also, thehardness of the graphite is, for example, preferably 10 GPa or less,more preferably 5 GPa or less, particularly preferably 3 GPa or less.Here, the nanoindentation method is a method such that an indenter (suchas a needle of a nano-order) is pushed into a material surface tomeasure hardness and Young's modulus in a micro area from load anddisplacement magnitude, which method has the advantage that dispersionof numerical values may be lessened to measure numerical values withfavorable precision. Specifically, the graphite as an anode activematerial was embedded in resin and ground to measure the hardness of thegraphite on a surface thereof twenty times by using a nanoindenter(manufactured by Agilent Technologies). The obtained numerical valuesmay be averaged to calculate the hardness.

Also, the graphite is not particularly limited if the graphite is suchas to have the hardness described above, but is preferably such that therelative ratio of the edge plane existing on the surface of the graphiteis a predetermined value or more. Such a relative ratio of the edgeplane existing on the surface of the graphite is measured in thefollowing manner. That is to say, the ratio is measured from anI₀₀₂/I₁₁₀ value after pressing at a pressure of 4.3 ton/cm² in the caseof regarding X-ray diffraction intensity of a peak on (002) plane of thegraphite as I₀₀₂ and X-ray diffraction intensity of a peak on (110)plane of the graphite as I₁₁₀. Here, (002) plane of the graphitecorresponds to a basal plane and (110) plane corresponds to an edgeplane. Thus, in the embodiment, from the viewpoint of insertion anddesorption of a conductive ion, the I₀₀₂/I₁₁₀ value as diffractionintensity ratio is preferably smaller, for example, preferably the samerange (specifically 200 or less) as the second embodiment and fourthembodiment described later. Incidentally, a calculation method for thediffraction intensity ratio is described later.

The graphite is not particularly limited if the graphite is such as tohave the hardness described above, but may be artificial graphite ornatural graphite; among them, artificial graphite may be appropriatelyused.

Examples of the shape of the graphite as an anode active materialinclude a particulate shape and a filmy shape. Also, the averageparticle diameter of the graphite is preferably, for example, within arange of 0.1 μm to 50 μm, above all, within a range of 1 μm to 50 μm,and within a range of 1 μm to 20 μm, further, within a range of 5 μm to15 μm. Incidentally, the average particle diameter may be measured withobservation by a scanning electron microscope (SEM), for example. Also,the content of the anode active material in the anode active materiallayer is, for example, preferably within a range of 10% by weight to 99%by weight, more preferably within a range of 20% by weight to 90% byweight.

(ii) Sulfide Solid Electrolyte

The sulfide solid electrolyte material in the embodiment is notparticularly limited if the sulfide solid electrolyte material is suchas to contain sulfur and have ion conductivity. The sulfide solidelectrolyte has a soft and fragile property as compared with an oxidebased solid electrolyte, for example. Thus, the application of confiningpressure to the battery element allows the sulfide solid electrolyte toeasily change (crush) in shape and enter a gap existing in the graphiteas an anode active material. Thus, the anode active material layerexcellent in ion conductivity may be obtained.

Examples of the sulfide solid electrolyte in the embodiment includeLi₂S—P₂S₅, Li₂S—P₂S₅—LiI, Li₂S—P₂S₅—Li₂O, Li₂S—P₂S₅—Li₂O—LiI, Li₂S—SiS₂,Li₂S—SiS₂—LiI, Li₂S-SiS₂—LiBr, Li₂S—SiS₂—LiCl, Li₂S—SiS₂—B₂S₃—LiI,Li₂S—SiS₂—P₂S₅—LiI, Li₂S—B₂S₃, Li₂S—P₂S₅—Z_(m)S_(n) (“m” and “n” arepositive numbers; Z is any of Ge, Zn and Ga; for example,Li_(3.25)P_(0.25)Ge_(0.76)S₄), Li₂ 13 GeS₂, Li₂S—SiS₂—Li₃PO₄, andLi₂S—SiS₂—Li_(x)MO_(y) (“x” and “y” are positive numbers; M is any of P,Si, Ge, B, Al, Ga and In). Above all, Li₂S—P₂S₅ may be appropriatelyused.

Incidentally, the description of the “Li₂S—P₂S₅” refers to the sulfidesolid electrolyte obtained by using a raw material compositioncontaining Li₂S and P₂S₅, and the same is applied to other descriptions.

Also, in the case where the sulfide solid electrolyte is obtained byusing a raw material composition containing Li₂S and P₂S₅, the ratio ofLi₂S to the total of Li₂S and P₂S₅ is, for example, preferably within arange of 70 mol % to 80 mol %, more preferably within a range of 72 mol% to 78 mol %, and far more preferably within a range of 74 mol % to 76mol %. The reason therefor is that this allows the sulfide solidelectrolyte having an ortho-composition or a composition in theneighborhood of it and allows the sulfide solid electrolyte with highchemical stability. Here, ortho generally means oxo acid which is thehighest in degree of hydration among oxo acids obtained by hydrating thesame oxide. In the present invention, a crystal composition to which thegreatest amount of Li₂S is added among sulfides is called anortho-composition. Li₃PS₄ corresponds to the ortho-composition in theLi₂S—P₂S₅ system. In the case of an Li₂S—P₂S₅-based sulfide solidelectrolyte, the ratio of Li₂S and P₂S₅ such as to allow theortho-composition is Li₂S:P₂S₅=75:25 on a molar basis. Incidentally,also in the case of using Al₂S₃ or B₂S₃ instead of P₂S₅ in the sulfidesolid electrolyte, the preferable range is the same. Li₃AlS₃ correspondsto the ortho-composition in the Li₂S—Al₂S₃ system and Li₃BS₃ correspondsto the ortho-composition in the Li₂S—B₂S₃ system.

Also, in the case where the sulfide solid electrolyte is obtained byusing a raw material composition containing Li₂S and SiS₂, the ratio ofLi₂S to the total of Li₂S and SiS₂ is, for example, preferably within arange of 60 mol % to 72 mol %, more preferably within a range of 62 mol% to 70 mol %, and far more preferably within a range of 64 mol % to 68mol %. The reason therefor is that this allows the sulfide solidelectrolyte having an ortho-composition or a composition in theneighborhood of it and allows the sulfide solid electrolyte with highchemical stability. Li₄SiS₄ corresponds to the ortho-composition in theLi₂S—SiS₂ system. In the case of an Li₂S—SiS₂-based sulfide solidelectrolyte, the ratio of Li₂S and SiS₂ such as to allow theortho-composition is Li₂S:SiS₂=66.7:33.3 on a molar basis. Incidentally,also in the case of using GeS₂ instead of SiS₂ in the sulfide solidelectrolyte, the preferable range is the same. Li₄GeS₄ corresponds tothe ortho-composition in the Li₂S—GeS₂ system.

Also, in the case where the sulfide solid electrolyte is obtained byusing LiX (X═Cl, Br and I), the ratio of LiX is, for example, preferablywithin a range of 1 mol % to 60 mol %, more preferably within a range of5 mol % to 50 mol %, and far more preferably within a range of 10 mol %to 40 mol %. Also, in the case where the sulfide solid electrolyte isobtained by using Li₂O, the ratio of Li₂O is, for example, preferablywithin a range of 1 mol % to 25 mol %, more preferably within a range of3 mol % to 15 mol %.

The sulfide solid electrolyte in the present invention may be sulfideglass, or crystallized sulfide glass obtained by heat-treating thesulfide glass. The sulfide glass may be obtained by amorphizationtreatment such as a mechanical milling method and a melt extractionmethod. On the other hand, the crystallized sulfide glass may beobtained by heat-treating the sulfide glass, for example.

The content of the sulfide solid electrolyte in the anode activematerial layer is, for example, preferably within a range of 1% byweight to 90% by weight, more preferably within a range of 10% by weightto 80% by weight.

(iii) Anode Active Material Layer

The anode active material layer may further contain a conductivematerial and a binder as required. Examples of the conductive materialinclude carbon black such as acetylene black and Ketjen Black, andcarbon fiber. The addition of such a conductive material allows electronconduction of the anode active material layer to be improved. Also,examples of the binder include fluorine-containing binders such as PTFEand PVDF.

The voidage of the anode active material layer is not particularlylimited if the voidage is such as to allow sufficient energy density,but is, for example, preferably the same range (specifically 30% orless) as the third embodiment and fourth embodiment described later.Incidentally, a calculation method for the voidage is described later.Also, the thickness of the anode active material layer may be properlydetermined in accordance with kinds of an intended all solid statebattery, and is preferably, for example, within a range of 0.1 μm to1000 μm, above all, within a range of 10 μm to 100 μm, further, within arange of 10 μm to 50 μm.

(2) Solid Electrolyte Layer

The solid electrolyte layer in the embodiment is a layer containing atleast a solid electrolyte. Examples of the solid electrolyte used forthe present invention include an oxide based solid electrolyte and asulfide solid electrolyte, preferably a sulfide solid electrolyte amongthem. Incidentally, the same sulfide solid electrolyte as for the anodeactive material layer may be used. Also, a polymer electrolyte and a gelelectrolyte except the oxide based solid electrolyte and sulfide solidelectrolyte may be used as the solid electrolyte layer.

Examples of the polymer electrolyte include a polymer electrolytecontaining a lithium salt and a polymer. The lithium salt is notparticularly limited if the lithium salt is a lithium salt used for ageneral lithium battery, but examples thereof include LiPF₆, LIBF₄,LiN(CF₃SO₂)₂, LiCF₃SO₃, LiC₄F₉SO₃, LiC(CF₃SO₂)₃ and LiClO₄. The polymeris not particularly limited if the polymer is such as to form a complexwith the lithium salt, but specific examples thereof includepolyethylene oxide.

Examples of the gel electrolyte include a gel electrolyte containing alithium salt, a polymer and a nonaqueous solvent. The same lithium saltas for the polymer electrolyte may be used. The nonaqueous solvent isnot particularly limited if the nonaqueous solvent may dissolve thelithium salt, but examples thereof include propylene carbonate, ethylenecarbonate, diethyl carbonate, dimethyl carbonate, ethyl methylcarbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, acetonitrile,propionitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane,1,3-dioxolane, nitromethane, N,N-dimethylformamide, dimethyl sulfoxide,sulfolane and y-butyrolactone. These nonaqueous solvents may be used byonly one kind or by mixture of two kinds or more. Also, anambient-temperature molten salt may be used as a nonaqueous liquidelectrolyte. Also, the polymer is not particularly limited if thepolymer may be gelatinized, but examples thereof include polyethyleneoxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride(PVDF), polyurethane, polyacrylate and cellulose.

The content of the solid electrolyte in the solid electrolyte layer ispreferably, for example, 60% by weight or more, above all, 70% by weightor more, and particularly, 80% by weight or more. The solid electrolytelayer may consist of only the solid electrolyte described above, orcontain a binder. Incidentally, the same binder as for the anode activematerial layer may be used. Also, the thickness of the solid electrolytelayer may be properly determined in accordance with constitutions of anintended all solid state battery, and is preferably, for example, withina range of 0.1 μm to 1000 μm, above all, within a range of 0.1 μm to 300μm.

(3) Cathode Active Material Layer

The cathode active material layer in the embodiment is a layercontaining at least a cathode active material, and may further containat least one of a solid electrolyte, a conductive material and a binderas required.

The cathode active material in the embodiment is properly selected inaccordance with kinds of a conductive ion of an intended all solid statebattery, and is not particularly limited if the cathode active materialoccludes and releases a conductive ion (such as Li ion). Also, thecathode active material may be an oxide cathode active material or asulfide cathode active material.

Examples of the oxide active material used as the cathode activematerial include rock salt bed type active materials such as LiCoO₂,LiMnO₂, LiNiO₂, LiVO₂ and LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂, spinel typeactive materials such as LiMn₂O₄ and LiNi_(0.5)Mn_(1.5)O₄, olivine typeactive materials such as LiFePO₄ and LiMnPO₄, and Si-containing activematerials such as Li₂FeSiC₄ and Li₂MnSiO₄. Also, examples of the oxideactive material except the above include Li₄Ti₅O₁₂. A coat layer forinhibiting a reaction with a sulfide solid electrolyte material ispreferably formed on the surface of the oxide active material. Thereason therefor is that this allows a high resistive layer to beinhibited from occurring by a reaction between the oxide active materialand the sulfide solid electrolyte. Examples of a material for the coatlayer include an oxide material having ion conductivity, and specificexamples thereof include lithium niobate. Also, examples of the sulfideactive material used as the cathode active material include copperChevrel (Cu₂Mo₆S₈), iron sulfide (FeS), cobalt sulfide (CoS) and nickelsulfide (NiS).

Examples of the shape of the cathode active material include aparticulate shape. The average particle diameter of the cathode activematerial is preferably, for example, within a range of 0.1 μm to 50 μm,above all, within a range of 1 μm to 50 μm, and within a range of 1 μmto 20 μm, further, within a range of 3 μm to 5 μm. Incidentally, theaverage particle diameter may be measured with observation by a scanningelectron microscope (SEM), for example. Also, the content of the cathodeactive material in the cathode active material layer is, for example,preferably within a range of 10% by weight to 99% by weight, morepreferably within a range of 20% by weight to 90% by weight.

The cathode active material layer preferably contains the solidelectrolyte further. The reason therefor is that this allows ionconductivity in the cathode active material layer to be improved.Incidentally, the same solid electrolyte contained in the cathode activematerial layer as for the anode active material layer may be used. Thecontent of the solid electrolyte in the cathode active material layeris, for example, preferably within a range of 1% by weight to 90% byweight, more preferably within a range of 10% by weight to 80% byweight.

The cathode active material layer may contain a conductive material anda binder as required. Incidentally, the same conductive material andbinder as for the anode active material layer may be used. Also, thethickness of the cathode active material layer may be properlydetermined in accordance with kinds of an intended all solid statebattery, and is preferably, for example, within a range of 0.1 μm to1000 μm, above all, within a range of 10 μm to 100 μm, further, within arange of 10 μm to 50 μm.

(4) Battery Element

The battery element in the embodiment has the cathode active materiallayer, the anode active material layer and the solid electrolyte layer,and is confined at a confining pressure more than 75 kgf/cm². Thus, thebattery element is confined at such a predetermined confining pressureas to allow expansion and contraction to be restrained. Therefore, evenin the case of repeatedly performing charge and discharge, an all solidstate battery with high durability may be obtained. The confiningpressure in the embodiment is not particularly limited if the confiningpressure is ordinarily more than 75 kgf/cm², but is, for example,preferably 150 kgf/cm² or more, more preferably 400 kgf/cm² or more. Thecase where the confining pressure is too smaller than the range causesthe sulfide solid electrolyte in the anode active material layer toenter a gap in the graphite with difficulty, and brings a possibility ofincreasing a gap existing in the anode active material layer. Therefore,an ion conduction path and an electron conduction path are formed withdifficulty to deteriorate battery performance. On the other hand, theconfining pressure is, for example, preferably 1000 kgf/cm² or less,more preferably 500 kgf/cm² or less. The reason therefor is that thecase where the confining pressure is too larger than the range causesthe shape of the graphite as an anode active material to be retainedwith difficulty. Therefore, a function as the anode active materialdescribed above deteriorates and the performance of the anode activematerial layer lowers. Also, the reason therefor is that space andweight of a constraint member for confining the battery element increaseto bring a possibility of saving space with difficulty.

The battery element ordinarily has a cathode current collector forcollecting the cathode active material layer and an anode currentcollector for collecting the anode active material layer in addition tothe cathode active material layer described above and the like. Examplesof a material for the cathode current collector include SUS, aluminum,nickel, iron, titanium and carbon. Also, examples of a material for theanode current collector include SUS, copper, nickel and carbon. Also,factors such as the thickness and shape of the cathode current collectorand the anode current collector are preferably selected properly inaccordance with uses of all the solid state battery and the like. Also,a general battery case may be used for a battery case to be used for theembodiment, and examples thereof include a battery case made of SUS.

(5) All Solid State Battery

The all solid state battery of the embodiment may have a constitutionexcept the battery element, and examples thereof include a member forapplying confining pressure to the battery element (a constraintmember). Such a constraint member is not particularly limited if theconstraint member allows a desired confining pressure to the batteryelement. Above all, the constraint member is preferably a member foruniformly applying confining pressure to the whole surface of thebattery element. Specific examples of such a constraint member include amember having at least a support plate. Also, a material for theconstraint member is not particularly limited if the material is amaterial endurable against a predetermined pressure, but examplesthereof include metal, resin and rubber.

Examples of kinds of the all solid state battery of the embodimentinclude an all solid lithium battery, an all solid sodium battery, anall solid magnesium battery and an all solid calcium battery; above all,preferably an all solid lithium battery. Also, the all solid statebattery in the embodiment may be a primary battery or a secondarybattery, preferably a secondary battery among them. The reason thereforis that it may be repeatedly charged and discharged and be useful as acar-mounted battery, for example. Incidentally, the primary batterymeans a battery available as a primary battery, that is, a battery whichis first charged sufficiently and thereafter discharged. Also, examplesof the shape of the all solid state battery of the embodiment include acoin shape, a laminate shape, a cylindrical shape and a rectangularshape. A method for producing the all solid state battery of theembodiment is not particularly limited if the method allows the allsolid state battery described above.

2. Second Embodiment

The all solid state battery of a second embodiment is an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has an I₀₀₂/I₁₁₀ value of 200 or less afterpressing at a pressure of 4.3 ton/cm² in the case of regarding X-raydiffraction intensity of a peak on (002) plane as I₀₀₂ and X-raydiffraction intensity of a peak on (110) plane as I₁₁₀, and the batteryelement is confined at a pressure more than 75 kgf/cm².

FIG. 4 is a schematic view showing an example of an anode activematerial layer included in the all solid state battery of theembodiment. As shown in FIG. 4, the anode active material layer 2contains graphite 2 a as an anode active material and a sulfide solidelectrolyte (not shown in the figure). The graphite 2 a has an I₀₀₂/I₁₁₀value of 200 or less after pressing at a pressure of 4.3 ton/cm² in thecase of regarding X-ray diffraction intensity of a peak on (002) planeas I₀₀₂ and X-ray diffraction intensity of a peak on (110) plane asI₁₁₀. In addition, the battery element 6 is confined at a confiningpressure more than 75 kgf/cm². Incidentally, reference numerals notdescribed in FIG. 4 are the same as FIGS. 1 and 2; therefore, thedescription here is omitted.

According to the present invention, the I₀₀₂/I₁₁₀ value after pressingat a pressure of 4.3 ton/cm² is within a predetermined range and thebattery element is confined at a predetermined confining pressure, sothat input characteristics during high rate charging improve. Thus, anall solid state battery suitable for high rate charging may be obtained.

Thus, the reason why the I₀₀₂/I₁₁₀ value after pressing at a pressure of4.3 ton/cm² is within a predetermined range and the battery element isconfined at confining pressure and thereby input characteristics duringhigh rate charging improve is guessed as follows. Here, (002) plane ofthe graphite corresponds to a basal plane and (110) plane corresponds toan edge plane. As described in the section “1. First embodiment”, aconductive ion (such as Li ion) is inserted and desorbed on an edgeplane, and a conductive ion is not inserted and desorbed on a basalplane. In the case where the I₀₀₂/I₁₁₀ value is not within apredetermined range, it is conceived that the ratio of the edge planeexisting on the surface of the graphite is relatively low, and the ratioof the basal plane is relatively high. Accordingly, it is conceived thatan ion conduction path and an electron conduction path are not secured,and a function as the active material is not sufficiently obtained. Incontrast, in the embodiment, the I₀₀₂/I₁₁₀ value is within such apredetermined range that the relative ratio of the edge plane on thesurface of the graphite is secured, and an ion conduction path and anelectron conduction path are secured. In addition, in the embodiment, itis conceived that the battery element is confined at such apredetermined confining pressure that a sulfide solid electrolyte iscrushed so moderately as to easily enter a gap in the graphite. Thus, ananode active material layer more excellent in ion conductivity may beobtained. Accordingly, input characteristics during high rate chargingimprove and an all solid state battery suitable for high rate chargingmay be obtained.

The anode active material layer in the embodiment is a layer containinggraphite as an anode active material and a sulfide solid electrolyte.The graphite is not-particularly limited if the I₀₀₂/I₁₁₀ value afterpressing at a pressure of 4.3 ton/cm² is 200 or less, but the I₀₀₂/I₁₁₀value is preferably a smaller value from the viewpoint of insertion anddesorption of a conductive ion.

The I₀₀₂/I₁₁₀ value is ordinarily 200 or less, for example, preferably100 or less, more preferably 50 or less. The reason therefor is that thecase where the I₀₀₂/I₁₁₀ value is more than the range brings apossibility that the ratio of the edge plane involved in insertion anddesorption of a conductive ion becomes relatively low on the surface ofthe graphite. Thus, an ion conduction path and an electron conductionpath are secured with difficulty. Here, examples of a measuring methodfor the X-ray diffraction intensity include X-ray diffraction (XRD)measurement using CuKα ray. Specifically, the X-ray diffractionintensity may be obtained by measuring each of an intensity of adiffraction peak for indicating (002) plane, which appears in a positionof a diffraction angle 2θ=26.5°±1.0°, and an intensity of a diffractionpeak for indicating (110) plane, which appears in a position of adiffraction angle 2θ=77.5°±1.0° (particularly, 2θ=77.5°±0.03′).Incidentally, the I₀₀₂/I₁₁₀ value may be a value obtained by XRDmeasuring the anode active material layer containing the graphite as ananode active material and another constitution such as the sulfide solidelectrolyte described later after pressing at a pressure of 4.3 ton/cm²,or a value obtained by XRD measuring a laminated body, in which theanode active material layer, the solid electrolyte layer and the cathodeactive material layer described above are laminated, after pressing at apressure of 4.3 ton/cm². The reason therefor is that the sulfide solidelectrolyte contained in the anode active material layer is such acomparatively soft material that the I₀₀₂/I₁₁₀ value obtained bymeasuring the graphite after pressing at the pressure described aboveand the I₀₀₂/I₁₁₀ value obtained by measuring the anode active materiallayer after pressing at the pressure described above are approximatevalues.

Also, the graphite as an anode active material preferably has a hardnessof 0.36 GPa or more, for example. As described in the section “1. Firstembodiment”, it is conceived that the relative ratio between the edgeplane and the basal plane on the surface of the graphite changes inaccordance with shape change of the graphite. Thus, the graphite hassuch a predetermined hardness as to bring a high possibility that theshape of the graphite may be retained even though the battery element isconfined at a predetermined confining pressure. Thus, the relative ratioof the edge plane existing on the surface of the graphite is maintained,and an ion conduction path and an electron conduction path are secured.

With regard to the anode active material layer in the embodiment, thevoidage thereof is not particularly limited if the voidage is such as tosecure an ion conduction path and an electron conduction path, but is,for example, preferably the same range (specifically 30% or less) as thethird embodiment and fourth embodiment described later. Incidentally, acalculation method for the voidage is described later.

The material and shape of an anode active material in the embodiment, oranother constitution of the anode active material layer in theembodiment are the same as that in the section “1. First embodiment”.

The battery element in the embodiment has the cathode active materiallayer, the anode active material layer and the solid electrolyte layer,and is confined at a confining pressure more than 75 kgf/cm².Incidentally, the confining pressure is the same as defined in the firstembodiment. Also, the cathode active material layer, the solidelectrolyte layer, another constitution of the battery element, andanother item of the all solid state battery in the embodiment are thesame as those described in the section “1. First embodiment”; therefore,the description here is omitted.

3. Third Embodiment

The all solid state battery of a third embodiment is an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has a hardness of 0.36 GPa or more by ananoindentation method, and a voidage of the anode active material layeris 30% or less.

FIG. 5 is a schematic view showing an example of an anode activematerial layer included in the all solid state battery of theembodiment. As shown in FIG. 5, the anode active material layer 2contains graphite 2 a as an anode active material and a sulfide solidelectrolyte (not shown in the figure). With regard to the graphite 2 a,a hardness calculated by a nanoindentation method is 0.36 GPa or more.Also, the voidage in the anode active material layer 2 is 30% or less.Incidentally, reference numerals not described in FIG. 5 are the same asFIGS. 1 and 2; therefore, the description here is omitted.

According to the present invention, the graphite as an anode activematerial has a predetermined hardness and the voidage of the anodeactive material layer is within a predetermined range, so that inputcharacteristics during high rate charging improve. Thus, an all solidstate battery suitable for high rate charging may be obtained.

Thus, the reason why the graphite has a predetermined hardness and thevoidage of the anode active material layer is within a predeterminedrange and thereby input characteristics during high rate chargingimprove is guessed as follows. That is to say, in the anode activematerial layer, the voidage is preferably smaller from the viewpoint ofimproving ion conductivity of the solid electrolyte material containedin the anode active material layer. Also, in the case where the voidageof the anode active material layer is within a predetermined range, whenthe graphite as an anode active material does not have a predeterminedhardness, there is a possibility that the shape of the graphite may notsufficiently be retained. Thus, as described in the section “l. Firstembodiment”, the ratio of the edge plane existing on the surface of thegraphite decreases relatively, and the ratio of the basal planeincreases relatively. Accordingly, it is conceived that an ionconduction path and an electron conduction path are not secured, and afunction of the graphite as the active material deteriorates. Incontrast, in the embodiment, the graphite has such a sufficient hardnessthat the shape of the graphite may be sufficiently retained in the casewhere the voidage of the anode active material layer is within apredetermined range. Thus, it is conceived that the ratio of the edgeplane existing on the surface of the graphite is maintained and an ionconduction path is secured. Accordingly, input characteristics duringhigh rate charging improve and an all solid state battery suitable forhigh rate charging may be obtained.

The anode active material layer in the embodiment is a layer containingthe graphite as an anode active material and the sulfide solidelectrolyte, and having a voidage of 30% or less. Also, with regard tothe graphite, a hardness calculated by a nanoindentation method is 0.36GPa or more. Here, the graphite, the sulfide solid electrolyte, oranother constitution of the anode active material layer may be the sameas in the section “1. First embodiment”.

The voidage in the anode active material layer is not particularlylimited if the voidage is ordinarily 30% or less. Here, the “voidage”means the voidage of the anode active material layer in the obtainedbattery element, which is produced so as to include a cathode activematerial layer, a solid electrolyte layer, and an anode active materiallayer. The voidage is preferably 15% or less, for example. The reasontherefor is that the case where the voidage is more than the rangebrings a possibility of lowering energy density in the anode activematerial layer. Thus, battery characteristics deteriorate. Here,examples of a calculation method for the voidage include a method forcalculating by using the following expression.

voidage (%)=100−filling factor (%)=100−(volume of anode active materiallayer calculated from true density)/(volume of real anode activematerial layer)

Incidentally, “volume of anode active material layer calculated fromtrue density” in the expression means the total of volumes obtained bydividing the weight of each material (such as anode active material andsulfide solid electrolyte) contained in the anode active material layerby the true density of each material, and “volume of real anode activematerial layer” means volumes calculated from sizes of the real anodeactive material layer.

The battery element in the embodiment is not particularly limited if thebattery element is such as to contain the anode active material layerdescribed above, but is preferably confined at a predetermined confiningpressure, for example. The confining pressure is properly determined inaccordance with the voidage of the intended anode active material layer,and is, for example, preferably in the same range (specifically 75kgf/cm² or more) as the first embodiment and second embodiment describedabove. Also, another constitution of the battery element and anotheritem of the all solid state battery in the embodiment are the same asthose described in the section “1. First embodiment”; therefore, thedescription here is omitted.

4. Fourth Embodiment

The all solid state battery of a fourth embodiment is an all solid statebattery comprising a battery element having a cathode active materiallayer, an anode active material layer, and a solid electrolyte layerformed between the cathode active material layer and the anode activematerial layer, characterized in that the anode active material layercontains graphite as an anode active material and a sulfide solidelectrolyte, the graphite has an I₀₀₂/I₁₁₀ value of 200 or less afterpressing at a pressure of 4.3 ton/cm² in the case of regarding X-raydiffraction intensity of a peak on (002) plane as I₀₀₂ and X-raydiffraction intensity of a peak on (110) plane as I₁₁₀, and a voidage ofthe anode active material layer is 30% or less.

FIG. 6 is a schematic view showing an example of an anode activematerial layer included in the all solid state battery of theembodiment. As shown in FIG. 6, the anode active material layer 2contains graphite 2 a as an anode active material and a sulfide solidelectrolyte (not shown in the figure). The graphite 2 a has an I₀₀₂/I₁₁₀value of 200 or less in the case of regarding X-ray diffractionintensity of a peak on (002) plane as I₀₀₂ and X-ray diffractionintensity of a peak on (110) plane as I₁₁₀. Also, the voidage of theanode active material layer 2 in the battery element 6 is 30% or less.Incidentally, reference numerals not described in FIG. 6 are the same asFIGS. 1 and 2; therefore, the description here is omitted.

According to the present invention, the I₀₀₂/I₁₁₀ value after pressingat a pressure of 4.3 ton/cm² is within a predetermined range and thevoidage of the anode active material layer is within a predeterminedrange, so that input characteristics during high rate charging improveand an all solid state battery suitable for high rate charging may beobtained.

Thus, the reason why the I₀₀₂/I₁₁₀ value after pressing at a pressure of4.3 ton/cm² is within a predetermined range and the voidage of the anodeactive material layer is within a predetermined range and thereby inputcharacteristics during high rate charging improve is guessed as follows.That is to say, as described in the section “2. Second embodiment”, aconductive ion (such as Li ion) is inserted and desorbed on an edgeplane (corresponding to (110) plane of the graphite), and a conductiveion is not inserted and desorbed on a basal plane (corresponding to(002) plane of the graphite). Thus, in the case where the I₀₀₂/I₁₁₀value is not within a predetermined range, it is conceived that theratio of the edge plane existing on the surface of the graphite isrelatively low, and the ratio of the basal plane is relatively high.Accordingly, it is conceived that an ion conduction path and an electronconduction path are not secured, and a function as the active materialis not sufficiently obtained. Also, as described in the section “3.Third embodiment”, the voidage in the anode active material layer ispreferably smaller from the viewpoint of improving ion conductivity ofthe solid electrolyte material contained in the anode active materiallayer. Accordingly, input characteristics during high rate chargingimprove and an all solid state battery suitable for high rate chargingmay be obtained.

The anode active material layer in the embodiment is a layer containingthe graphite as an anode active material and the sulfide solidelectrolyte layer. Also, the graphite has the I₀₀₂/I₁₁₀ value of 200 orless. Such graphite may be the same as in the section “2. Secondembodiment”.

The anode active material layer is not particularly limited if thevoidage is ordinarily 30% or less, but may be the same as in the section“3. Third embodiment”.

Another constitution of the anode active material layer, anotherconstitution of the battery element, and another item of the all solidstate battery in the embodiment are the same as those described in thesection “1. First embodiment”; therefore, the description here isomitted.

Incidentally, the present invention is not limited to theabove-mentioned embodiments. The above-mentioned embodiments areexemplification, and any is included in the technical scope of thepresent invention if it has substantially the same constitution as thetechnical idea described in the claim of the present invention andoffers similar operation and effect thereto.

EXAMPLES

The present invention is described more specifically while showingexamples hereinafter.

Example 1

(Synthesis of Sulfide Solid Electrolyte)

First, lithium sulfide (Li₂S) and diphosphorus pentasulfide (P₂S₅) wereused as a starting material. These powders were weighed in a glove boxunder an Ar atmosphere (dew-point temperature: −70° C.) so as to becomea molar ratio of Li₂S:P₂S₅=70:30. Projected into a 45-ml zirconia potwas 1 g of this mixture, and zirconia ball (φ=10 mm, 10 pieces) wasfurther projected thereinto to hermetically seal the pot completely (Aratmosphere). This pot was mounted on a planetary ball milling machine(p7™ manufactured by FRITSCH JAPAN CO., LTD.) to perform mechanicalmilling for 20 hours at the number of soleplate revolutions of 370 rpmand then obtain sulfide glass. Thereafter, the obtained sulfide glasswas heated in Ar and crystallized. The heating conditions were theconditions of heating from room temperature up to 260° C. at 10°C./minute to thereafter cool to room temperature. Thus, crystallizedsulfide glass (sulfide solid electrolyte) having a composition of70Li₂S-30P₂S₅ was obtained.

(Production of Battery)

Slurry containing LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ (a cathode activematerial) coated with LiNbO₃ and the sulfide solid electrolyte describedabove at a volume ratio of 6:4 was coated on an aluminum foil (a cathodecurrent collector) to obtain a cathode. Next, graphite (an anode activematerial) and the sulfide solid electrolyte described above wereprepared into an anode mixture so as to be at a volume ratio of 6:4, andslurry containing the anode mixture was coated on a copper foil toobtain an anode. In addition, slurry containing the sulfide solidelectrolyte described above was coated on an anode active material layerof the obtained anode to form a solid electrolyte layer. Next, the anodeand the cathode were laminated so that the solid electrolyte layerformed on the anode and a cathode active material layer of the cathodecontact, and pressed at a pressure of 4.3 ton/cm² to thereby obtain abattery element with the composition shown in FIG. 1. The obtainedbattery element was confined at a pressure of 450 kgf/cm². An evaluationbattery was produced by using the obtained battery element.Incidentally, the voidage of the anode active material layer in theobtained evaluation battery was 9%.

Examples 2 to 4

An evaluation battery was obtained in the same manner as Example 1except that the battery element was confined at a pressure of the valueas shown in Table 1.

Comparative Example 1

An evaluation battery was obtained in the same manner as Example 1except that graphite with a hardness of 0.35 GPa was used as the anodeactive material.

Comparative Examples 2 to 4

An evaluation battery was each obtained in the same manner asComparative Example 1 except that the battery element was confined at apressure of the value as shown in Table 1.

[Evaluations]

(Hardness Measurement of Graphite)

In Examples 1 to 4 and Comparative Examples 1 to 4, the graphite as ananode active material was embedded in resin and ground to measure thehardness of the graphite on a surface thereof twenty times by using ananoindenter (manufactured by Agilent Technologies). The obtainednumerical values were averaged and regarded as the hardness of thegraphite. The results are shown in Table 1. Incidentally, themeasurement conditions are an indentation depth of 500 nm and ameasurement mode of CSM.

(X-ray Diffraction Measurement)

In Examples 1 to 4 and Comparative Examples 1 to 4, the graphite used asan anode active material was prepared into powder. Put in a vessel of 1cm² was 100 mg of the prepared anode mixture and pressed at a pressureof 4.3 ton/cm². The graphite after being pressed was subject to X-raydiffraction (XRD) measurement to obtain diffraction intensity ratioI₀₀₂/I₁₁₀. Incidentally, XRD measurement was performed under an inertatmosphere on the condition of using CuKα ray. Specifically, I₀₀₂/I₁₁₀was calculated from an intensity of a diffraction peak for indicating(002) plane, which appears in a position of 2θ=26.5°±1.0°, and anintensity of a diffraction peak for indicating (110) plane, whichappears in a position of 2θ=77.5°±0.03°. The results are described inTable 1.

(Measurement of Charging Capacity)

The evaluation battery each obtained in Examples 1 to 4 and ComparativeExamples 1 to 4 was left at a temperature of 25° C. for 3 hours tothereafter perform charge and discharge at ⅓C rate. Thereafter, chargeand discharge were performed at 1.5C rate to measure the capacity of theanode such as to allow ordinary charge with no descent of voltage.Incidentally, the “descent of voltage” means a descent of voltage by 0.2mV or more in a short period. The results are shown in Table 1.

TABLE 1 Diffrac- ⅓ C 1.5 C tion In- Con- Charg- Charg- Hard- tensityfining Void- ing Ca- ing Ca- ness Ratio Pressure age pacity pacity (Gpa)(I₀₀₂/I₁₁₀) (kgf/cm²) (%) (mAh/g) (mAh/g) Example 1 0.64 25 450 9 202120 Example 2 0.64 25 150 15 157 80 Example 3 0.64 25 75 18 141 40Example 4 0.64 25 15 22 126 12 Compara- 0.35 246 450 8 197 97 tiveExample 1 Compara- 0.35 246 150 12 138 73 tive Example 2 Compara- 0.35246 75 13 117 51 tive Example 3 Compara- 0.35 246 15 15 105 32 tiveExample 4

Any of Examples 1 to 2 and Comparative Examples 1 to 2 is such that thebattery element is confined at a pressure more than 75 kgf/cm². As shownin Table 1, in comparing Example 1 and Comparative Example 1 with aconfining pressure of 450 kgf/cm², it may be confirmed that Example 1exhibits higher charging capacity at both low rate (⅓C) and high rate(1.5C). Also, in comparing Example 2 and Comparative Example 2 with aconfining pressure of 150 kgf/cm², it may be confirmed that Example 2exhibits higher charging capacity at both low rate and high rate. Thus,in the case where the battery element is confined at a predeterminedpressure, with regard to the graphite used as an anode active material,it may be confirmed that high charging capacity is obtained in high ratecharging by determining a hardness calculated by a nanoindentationmethod at 0.64 GPa as a predetermined value (0.36 GPa) or more, ordetermining a diffraction intensity ratio I₀₀₂/I₁₀₀ value at 25 as lessthan a predetermined value (200).

Also, in Table 1, it may be confirmed that the voidages of the anodeactive material layer are identical in Example 2 and Comparative Example4. In comparing Example 2 and Comparative Example 4, it may be confirmedthat the charging capacity of Example 2 becomes higher at both low rateand high rate. Here, through the results of Table 1, in Examples 1 to 4and Comparative Examples 1 to 4, the charging capacity at low rate andhigh rate tends to lower as the voidage becomes higher. Thus, in a range(such as 30% or less) of the voidage such as to include Examples 1 to 4and Comparative Examples 1 to 4, in the evaluation batteries for whichthe voidages of the anode active material layer are at a similar level,with regard to the graphite used as an anode active material, it may beconfirmed that high charging capacity is obtained in high rate chargingby determining a hardness calculated by a nanoindentation method at 0.64GPa as a predetermined value (0.36 GPa) or more, or determining adiffraction intensity ratio I₀₀₂/I₁₁₀ value at 25 as less than apredetermined value (200).

REFERENCE SIGNS LIST

-   1 . . . cathode active material layer-   2 . . . anode active material layer-   2 a . . . graphite (anode active material)-   3 . . . solid electrolyte layer-   4 . . . cathode current collector-   5 . . . anode current collector-   6 . . . battery element-   10 . . . all solid state battery

1-4. (canceled)
 5. An all solid state battery comprising a batteryelement having a cathode active material layer, an anode active materiallayer, and a solid electrolyte layer formed between the cathode activematerial layer and the anode active material layer, wherein the anodeactive material layer contains graphite as an anode active material anda sulfide solid electrolyte, the graphite has a hardness of 0.36 GPa ormore by a nanoindentation method, and the battery element is confined ata pressure 150 kgf/cm² or more.
 6. The all solid state battery accordingto claim 5, wherein the graphite has an I₀₀₂/I₁₁₀ value of 200 or lessafter pressing at a pressure of 4.3 ton/cm² in the case of regardingX-ray diffraction intensity of a peak on (002) plane as I₀₀₂ and X-raydiffraction intensity of a peak on (110) plane as I₁₁₀.
 7. An all solidstate battery comprising a battery element having a cathode activematerial layer, an anode active material layer, and a solid electrolytelayer formed between the cathode active material layer and the anodeactive material layer, wherein the anode active material layer containsgraphite as an anode active material and a sulfide solid electrolyte,the graphite has an I₀₀₂/I₁₁₀ value of 200 or less after pressing at apressure of 4.3 ton/cm² in the case of regarding X-ray diffractionintensity of a peak on (002) plane as I₀₀₂ and X-ray diffractionintensity of a peak on (110) plane as I₁₁₀, and the battery element isconfined at a pressure 150 kgf/cm² or more.
 8. The all solid statebattery according to claim 5, wherein a voidage of the anode activematerial layer is 30% or less.
 9. The all solid state battery accordingto claim 7, a voidage of the anode active material layer is 30% or less.